The efficiency of p-TSA treated clays was probed in the alkylation of p-cresol under solvent free microwave irradiation. The different aspects of the reaction studies include variation of temperature, duration of contact between the reactants, mole ratio of cresol to cyclohexanol and the clay treated with p-TSA to different extent. The acid strength as well as reaction parameters such as temperature and time were found to be the main factors controlling the reactivity and selectivity. The reaction was carried out in the temperature range 413–443 K. Lower temperature range favoured O-alkylation and higher temperatures yielded C-alkylated p-cresol. The catalyst retained its catalytic activity even after three consecutive runs. The results obtained with clays were compared with other solid acid catalysts such as aluminium exchanged clay, hydrochloric acid treated clay and K-10.